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<TITLE>Switch -HT[B|C] - select hash type [BLAKE2,CRC32] for file checksum</TITLE>
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[BLAKE2,CRC32] for file checksum">
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<P class="title"><A NAME="HELPSwHT"></A>Switch <B>-HT[B|C]</B>
-  select hash type [BLAKE2,CRC32] for file checksum<hr></P>

<p>File data integrity in RAR archive is protected by checksums
calculated and stored for every archived file.</p>

<p>By default, WinRAR uses CRC32 function to calculate the checksum.
<a href="HELPRAR5Format.htm">RAR 5.0</a> archive format also allows
to select BLAKE2 hash function instead of CRC32.</p>

<p>Specify -htb switch for BLAKE2 hash and -htc for CRC32 function.
Since CRC32 is the default algorithm, you may need -htc only to
override -htb mode in WinRAR configuration.</p>

<p>CRC32 output is 32 bit length. While CRC32 properties are suitable
to detect most of unintentional data errors, it is not reliable enough
to verify file data identity. In other words, if two files have
the same CRC32, it does not guarantee that file contents is the same.</p>

<p>BLAKE2 output is 256 bit. Being a cryptographically strong hash function,
it practically guarantees that if two files have the same value of BLAKE2,
their contents is the same. BLAKE2 error detection property is also
more reliable than in shorter CRC32.</p>

<p>Since BLAKE2 output is longer, resulting archive is a slightly larger
for -htb switch.</p>

<p>If archive headers are unencrypted (no <a href="HELPSwHP.htm">
switch -hp</a>), checksums for encrypted RAR 5.0 files are modified
using a special password dependent algorithm, to make impossible guessing
file contents based on checksums. Do not expect encrypted file checksums
to match usual CRC32 and BLAKE2 values.</p>

<p>This switch is supported only by RAR 5.0 format.</p>

<p>-htb is the command line equivalent of 
<a href="HELPGetArcOptions.htm#BLAKE2">Use BLAKE2 file checksum</a> option
in "Archive name and parameters" dialog.</p>


<h1><B>Example</B></h1>

<p>add *.lst to lists.rar using BLAKE2 for file checksums</p>

<p class="sample">WinRAR a -htb lists.rar *.lst</p>

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